Displaying and storing of photographs using a computer is becoming increasingly prevalent because of continuing improvements in hardware devices and increasing user demand. Larger capacity disk storage devices allow numerous images to be stored on a disk. Also, increasingly powerful central processing units (CPUs) allow convenient, rapid retrieval and browsing of these digital photographs. The development of the World-Wide Web has further increased the demand for digital photographs as businesses and individuals are developing their own Web pages which routinely include digital photographs.
Even though cameras directly producing a digital photograph are available, converting a conventional photograph into a digital photograph using a scanner attached to a computer remains a very common process. To accomplish this conversion, a photograph is first placed on the surface of a scanner. The size of this surface is typically several times the size of the photograph. The scanner is then activated to "scan" or digitize an image of its scanning surface. The digital image created by the scanner is usually in the form of a matrix or an array of picture elements ("pixels"); the matrix or array being proportionally sized to the size of the surface of the scanner. From this digital image, the "digital photograph" or portion representing the original photograph or object(s) must be extracted.
A first method for creating the desired digital photograph from this image is to use a digital image editor or drawing package. However, to achieve the desired digital photograph, the user must manually perform numerous, complex and tedious manipulation operations to edit the image on a pixel by pixel basis.
Overcoming some of the disadvantages of the first method, another common technique to extract the digital photograph begins with displaying the digital image on a computer monitor. The user then uses a pointing device (e.g., a mouse) to indicate a rectangular box encompassing the digital photograph, where the sides of the rectangular box are parallel to sides of the digital image. A crop function then extracts digital photograph from the larger digital image created from the scan. This process is very time consuming and requires complex user operations.
Both of these techniques require complex user interactions that are disadvantageous to the general acceptance of these scanning techniques by non-professional users. For example, in order for the digital photograph to contain an image of the actual photograph without extraneous information, either the photograph must be perfectly aligned on the scanner surface such that the sides of the photograph are parallel to that of the scanner surface, or complex editing of the digital image must be manually performed by the user as described above. A user might need to adjust and re-scan a photograph several time before proper alignment is achieved. And after these iterations, the user still will need to crop the image.
The overall time required for this extraction process can be decreased using a pre-scan step in which the scanner first performs a low-resolution (instead of a high-resolution) scan of the entire scanner surface. Like in the process described above, the user indicates via a pointing device a rectangular box encompassing the digital photograph. Then, an area of the scanner surface corresponding to that of the rectangular box is scanned at a higher resolution to acquire a high-resolution digital image. The corresponding portion of the high-resolution digital image within the rectangular box is extracted to form the desired digital photograph. This technique is faster than the previously described technique and requires less computer system memory because only a section of the scanner surface proportional to the size of the photograph is scanned at the higher resolution.
A known software system uses UMAX VistaScan Scanner Interface Software running under Adobe PhotoShop on a Macintosh computer for controlling a UMAX Vista scanner. This software has an "AutoScan Operation" which performs the following steps in the listed order: image preview, crop, deskew, scan mode detection, image quality adjustments, applying the scale factor, final scan, and applying "magic match". However, this software is hardware specific, requiring a UMAX scanner for proper operation which severely limits the acceptance of this techniques in the non-commercial consumer market.
There is a need for a digital image processing system in which the scanning and digital photograph extraction techniques described above and others can be automatically performed more easily, rapidly and accurately across all scanner peripherals.